Codechange: Remove write-only spec_id from RoadStopSpec. (#12582)

Comment is incorrect about its value too.

(cherry picked from commit 72c55128d2)

src/newgrf.cpp

@@ -5145,7 +5145,6 @@ static ChangeInfoResult RoadStopChangeInfo(uint id, int numinfo, int prop, const
 
 				uint32_t classid = buf->ReadDWord();
 				rs->cls_id = RoadStopClass::Allocate(BSWAP32(classid));
-				rs->spec_id = id + i;
 				break;
 			}
 

src/newgrf_roadstop.h

@@ -145,7 +145,6 @@ struct RoadStopSpec {
 	 */
 	GRFFilePropsBase<NUM_CARGO + 3> grf_prop;
 	RoadStopClassID cls_id;     ///< The class to which this spec belongs.
-	int spec_id;                ///< The ID of this spec inside the class.
 	StringID name;              ///< Name of this stop
 
 	RoadStopAvailabilityType stop_type = ROADSTOPTYPE_ALL;

src/table/newgrf_debug_data.h

@@ -2472,7 +2472,7 @@ class NIHRoadStop : public NIHelper {
 		const RoadStopSpec *spec = GetRoadStopSpec(index);
 		if (spec) {
 			uint class_id = RoadStopClass::Get(spec->cls_id)->global_id;
-			char *b = buffer + seprintf(buffer, lastof(buffer), "  class ID: %c%c%c%c, spec ID: %u", class_id >> 24, class_id >> 16, class_id >> 8, class_id, spec->spec_id);
+			char *b = buffer + seprintf(buffer, lastof(buffer), "  class ID: %c%c%c%c", class_id >> 24, class_id >> 16, class_id >> 8, class_id);
 			if (spec->grf_prop.grffile != nullptr) {
 				b += seprintf(b, lastof(buffer), "  (local ID: %u)", spec->grf_prop.local_id);
 			}